Papers by Keyword: Fatigue Test

Abstract: In this paper, micro tensile method was combined with micro bridge dynamic test method as a new testing method for mechanics performance to be put forward, and a novel testing system for mechanics properties of the thin-walled micro components was established. The micro testing specimen were designed and manufactured. And related mechanics performance tests were carried on to verify the feasibility and reliability of the test system. The experimental results show that displacements of the testing system are measured with 0.01μm resolution and axial loads are measured with 0.005N resolution.

Abstract: Lightweight and safe roof of the bus was solved within the MIT CR: FR-TI4/349 project. Several variants of sandwich roof were tested on samples in a prior period. Several errors of adhesive joints occurred during the production of the bus roof. Methyl methacrylate adhesive was tested with respect to the declared adhesive ability for arbitrary surfaces. Standardised shear test of the adhesive joints were made for tuning of the numerical model. The obtained parameters are used forthe numerical model of sandwich roof segment. Roof segments were loaded by four points bending and experimentally obtained data were compared with the results of numerical simulations. Several specimens were subjected to cyclic loading in order to get approximate fatigue life of tested variants.

Abstract: This article deals with fatigue tests of polymeric hollow fibre heat transfer surfaces. The hollow fibres have an outer diameter between 0.5-0.8 mm and wall thickness 10 % of the outer diameter. These plastic heat transfer surfaces have some limitations but also many benefits. One of the limitations is the durability of plastic under fatigue loading. The heat transfer surfaces were subjected to pulsating pressure loads under different conditions (level of pressure, ambient temperature, number of cycles). Firstly, only an internal hydraulic pulsating load was applied and the behaviour of the hollow fibres was observed, focusing especially on the presence of leaks, ruptures, etc.Then, other conditions of operations were added. The heat transfer surfaces were immersed in a hot bath and loaded by internal pulsating pressure and high temperature simultaneously. Testing under different temperatures is important because the temperature significantly affects the material properties. The presence of leaks, ruptures and other possible damage was monitored as with previous tests.

Abstract: Due to limitations of Conventional metallic biomaterials an attempt is made to develop a new hybrid polymer matrix composite for load bearing applications of Hip joints in the human body. Ultra high molecular weight polyethylene matrix material was blended with 50 wt% of short E-glass fibres and TiO₂ particles with varying percentage of reinforcement, using injection moulding machine. Fabricated composites specimens were subjected to tensile strength test, Fatigue test, SEM, Wear analysis test and In vivo Biocompatibility test to evaluate mechanical and tribological properties, required for bone joints load bearing applications. The maximum tensile strength of 41.5 MPa and young’s modulus of 7.5 GPa is obtained. The behavior of S-N curve obtained after the test is linear in nature, which leads to failure at 10⁵ cycles for the fabricated composite specimen. Also it reveals that fracture is due to brittle failure. The wear mechanism of composite specimen is, because of abrasion. Density of composite specimens was increased after dipping in the simulated body fluid solution.

Abstract: The paper explores laser welding of high-strength CP-W^® 800 steel and forged steel. Dissimilar welds were produced with different welding parameters. Two welding beam diameters were used. The microstructure and mechanical properties of the resulting welds were examined. Metallographic sections were prepared and microhardness and tension tests were carried out. Fatigue tests were conducted on the weld specimens to map the effects of welding parameters on the fatigue behaviour of the dissimilar weld between the CP steel and the forged steel. Greater amount of heat input impairs the strength of the joint but improves its resistance to initiation of fatigue cracks.

Abstract: To ascertain the grounding corrosion coefficient parking on the ground is the key to evaluate the airframe calendar life. The influence of pull and press load on the grounding corrosion coefficient was evaluated in this paper. The main results are as follows. First, the fatigue life always follows the logarithmic normal distribution after pre-corrosion for pull fatigue loading and press fatigue loading. But the scatter of fatigue life for the wing down-panels is reduced with the fatigue life, and the scatter of fatigue life for the wing up-panels is not changed. The second, the coefficient of the wing up-panels test sample is not changed with the increase of the corrosion calendar life. But, the coefficient of the wing down-panels test sample descends with the increase of the corrosion calendar life.

Abstract: Fatigue strength prediction methods of blades of a high pressure steam turbine are the main topic of this article. Experimental approaches, as well as use of the experimental results for the verification of the finite element method (FEM) and fatigue models, were performed on two basic levels. First, verification by the fatigue tests of smooth and notched cylindrical specimens under room and service conditions was performed. Second, verification of the real blade fatigue limit prediction was conducted. These tests were carried out using special test stand under the typical combined blades loading. Appropriate uniaxial and multiaxial fatigue criteria were applied. Achieved results were finally used in the process of the fatigue strength prediction of rotor blades.

Abstract: To solve the heavy vehicle leaf spring material issues, developed heavy vehicle leaf spring with a new material. This article focuses on technical solutions and new materials, materials testing trial and material properties, structure and toughening mechanism of tissue material analysis, leaf spring using new materials bench and road tests. The test results show that the new material with high strength, high ductility and excellent manufacturability. And fewer leaf spring meet material requirements, such as the high stress, high-performance and high reliability fatigue. The development of leaf spring using new materials has high fatigue properties, and it uses for liberation series replacement truck leaf spring.

Abstract: The overheat phenomenon often appears in the fatigue test of some high strength materials. It leads the deconcentration of test data and low efficiency of experiment process, or even failure of the whole test. The frequency adjusting method (FAM) and sample shape design technology are developed to solve this problem. Experiment result shows that the FAM can moderately ameliorate the overheat phenomenon. The resistivity of overheat phenomenon of the funnel type sample is far stronger than the straight bar type one.

Abstract: The rail fastener assemblies under alternating load for a long time , in addition to the vibration and strength,fatigue also is the main reason for damage .So effective fatigue test and life assessment is one of the important means to ensure the safety of railway operation .This paper introduces the routine fatigue test method of railway track fastener assembly which adopts the European Railway Standard EN13146-4,by using 33° test platform which conform to the actual operation stress conditions of the railway track can more effective test the rail fastening assembly.